1. Field of the Invention
This invention relates to a speed-change transmission apparatus, more particularly to a speed-change transmission apparatus having a continuously variable speed-change device and a planetary transmission section.
2. Description of Related Art
Examples of such conventional speed-change transmission apparatus are disclosed in e.g. Patent Document 1 and Patent Document 2.
The speed-change transmission apparatus disclosed in Patent Document 1 includes a unit having a variable displacement hydrostatic unit 4 and a fixed displacement hydrostatic unit 6, a planetary transmission section having a first planetary gear set 9, a second planetary gear set 10 and a planetary gear set 22 and a clutch section having a coupling 27, a coupling 32, a coupling 35 and a coupling 39.
The speed-change transmission apparatus disclosed in Patent Document 2 includes a hydraulic unit 4, a summator gear 10, a clutch section having clutches K1, K2, a planetary transmission section having a first planetary gear step 12 and a second planetary gear step 13, and another clutch section having clutches K3, K4.
Patent Document 1: U.S. Pat. No. 6,042,496
Patent Document 2: U.S. Pat. No. 5,911,645